A number of malt beverages or beers will produce a relatively good foam immediately after pouring, but the foams so produced are not as persistent as is usually desired by the consumers of such products. In addition, consumers desire a beer possessing a foam that will "cling" to the insides of a glass or mug in an attractive "lacy" pattern. Lace and cling are difficult to achieve in the presence of slight contaminant levels of surfactants or detergents on the glassware, as occurs when beer mugs or glasses are handwashed and quickly rinsed prior to use. A further requirement is that the beer exhibit good clarity to the consumer, i.e., the absence of any noticeable "haze".
Propylene glycol alginate (PGA), heteropolysaccharide S-10 (see U.S. Pat. No. 3,966,976) and cellulose ether (see U.S. Pat. No. 3 669 000) are additives known to stabilize beer foam.
However, continuing research is being conducted in an effort to discover new polymers, additives, and polymer combinations which may be more economical and which can be utilized to impart improved foam stability, lace, and clarity to fermented malt beverages while avoiding attendant "haze" levels.
Xanthan gum and galactomannans alone or in combination are described in the literature as extenders or thickeners in the food industry. U.S. Pat. No. 3,765,918 describes blends of pre-treated xanthan gum and guar gum which exhibit synergistically high viscosities in aqueous sols. However, there are no general references to such compositions being disclosed for specifically improving foam stability and properties of fermented malt beverages.